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Anyone viewing electron microscopic photographs, such as the ones published elsewhere in this issue, must be thrilled by the clarity of pictures at these magnifications. Not only is the fineness of detail esthetically satisfying, but the wealth of data that is there for the interpreting is scientifically provocative.
The limit of magnification with light microscopy is X 1000-2000, whereas that of "routine" electron microscopy is easily X 100,000. Optical resolution that was 100 Angstroms is now in the range of 6-8 Angstroms. The new order of magnitude has necessitated the invention of new terms and reinterpretation of old structures. Fenestrated membranes, long identified in the eye as the external limiting membrane of the retina and the inner membrane of the pigment epithelium (Wolfe calls it Verhoeff's membrane), consist of what the electron microscopists call terminal bars. They are not membranes at all but condensations of cytoplasm where intercellular exchanges are
C. DG. Electron Microscopy. Arch Ophthalmol. 1961;66(6):772–773. doi:10.1001/archopht.1961.00960010774002
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